Thinkpads Forum

Hi, I was mounting sxga+ screen using a modified cable and everything was fine the screen was working and everything was fine. But then when I wanted to do a final test before putting the screws on place the following happened:

1. screen doesn't light up. The picture is there, I can see it on the matrix.
2. the sensor on the cable (see the picture below) heats up. It becomes so hot that starts to melt plastic.

Here is the picture:
http://imgur.com/IJjeCky

The problem is not related to the screen or inverter. The same screen works fine with different cable. And the inverter as well is working. Its not the machine or cable connector (all checked with different combinations). The cable sensor heats up even with no screen or inverter attached. The machine doesn't even need to be on, it just needs to be plugged to power (no battery).

Seems like a short circuit, but where? inside the sensor ?
As you can see the sensor is surrounded with ceramic it seems solid. I know that I can try to cut it off and see, just wanted to hear you guys, maybe someone can suggest better solutions before doing amputation

vavet wrote: 2. the sensor on the cable (see the picture below) heats up. It becomes so hot that starts to melt plastic.

What is this???
It's seems that this sensor connects to lower part (that lives in Thinkpad body) of flex-PCB (LCD cable). I have removed keyboard from my X61 - and i haven't seen any sensors connected to LCD cable...

Big Brother is watching you through a sensor!

My guess would be that it's the Hall effect switch (sensor) which determines when the lid is open/closed. When operating correctly, it detects the presence or absence of a magnetic field. There should be a magnet mounted somewhere directly opposite of the sensor when the lid is in the closed position. It should definitely not get hot. Note that even though I own several X6x systems, I've not had the opportunity to tear one down. This guess is based upon your description of the screen's backlight being off. That's exactly what the Hall effect switch is meant to do.

If you cut it off, the laptop will lose the ability to detect the position of the lid. Depending upon how the switch interface is designed, that would mean that the backlight will always be off or on. If always off, I don't know if you could get it to turn on by shorting the two wires going to the now-missing sensor. In any event, my best recommendation would be to replace the flex cable.

rkawakami wrote:My guess would be that it's the Hall effect switch (sensor) which determines when the lid is open/closed. When operating correctly, it detects the presence or absence of a magnetic field. There should be a magnet mounted somewhere directly opposite of the sensor when the lid is in the closed position. It should definitely not get hot. Note that even though I own several X6x systems, I've not had the opportunity to tear one down. This guess is based upon your description of the screen's backlight being off. That's exactly what the Hall effect switch is meant to do.

If you cut it off, the laptop will lose the ability to detect the position of the lid. Depending upon how the switch interface is designed, that would mean that the backlight will always be off or on. If always off, I don't know if you could get it to turn on by shorting the two wires going to the now-missing sensor. In any event, my best recommendation would be to replace the flex cable.

Yes, It is a hall sensor that detects closed lid. I guess I have to cut it away.